Guests need a scuba tank, mask and fins to access the chamber, tethered to the pool floor about 15 feet below the surface. Once arrived, guests can remove their gear: The space, about six feet wide, has breathable air pumped inside, which means guests can get by with their lungs and nothing else.

After that, they're free to enjoy their €100 dinner, which generally features high-end foodstuffs like lobster, foie gras, and Champagne.